CN101458370B - Optical module - Google Patents

Abstract

A problem to be solved by the invention is to provide an optical module cheaper than the prior art. The invention provides an optical module comprising: a pedestal arranged on a CAN tube seat; at least a first light-emitting element and a first light-receiving element having different wavelength and arranged on one surface of the pedestal; a CAN cap fixed on the pedestal and having holes for light; and a parallel flat optical multiplexer having a first wavelength selective filter on one surface of the pedestal that has transmissivity to passing light and a mirror on the other surface. An extending direction of the optical multiplexer is fixed in the CAN cap or the package being tilted by an angle with respect to one surface of an optical element mounting board. Outgoing light from the first light-emitting element passes through the wavelength selective filter and the pedestal and enters an optical fibre outside the cap, and outgoing light from the optical fibre enters the optical multiplexer and is reflected by the wavelength selective filter and further reflected by the mirror, and then exits the optical multiplexer to enter the light-receiving element.

Description

optical module

technical field

The invention relates to an optical module, in particular to the structure of a bidirectional optical sending and receiving module for multiplexing or splitting light of multiple wavelengths.

Background technique

In the information communication field in recent years, the establishment of communication traffic for exchanging large-capacity data at high speed using light is rapidly proceeding. Especially with the explosive popularity of the Internet and the acceleration of broadband access lines, it can be seen that the market for FTTH (Fiber To The Home: Fiber To The Home) business has started significantly. Among the FTTH optical transmission methods, the PON (passive optical network: passive optical network) method in which multiple users share one optical fiber is currently increasing in demand. In this way, the data sent from the receiving station through one optical fiber is split into 16 to 32 optical fibers through the splitter, and distributed to each user's home, which can greatly reduce the cost of optical fiber laying. Lay ONU (Optical Network Unit: Optical Network Unit) on each user side as a terminal device, and pass the downlink signal (wavelength 1.5 μm) from the storage station to the user side and the uplink signal (wavelength 1.3 μm) from the user side to the storage station Perform wavelength multiplexing (WDM), and use the same optical fiber to transmit uplink and downlink signals. Furthermore, in the ONU, a 2-wavelength bidirectional optical module is loaded, and basically consists of a light-emitting element (LD: Laser Diode: Laser Diode) for uplink signal transmission and a light-receiving element (PD: Photo Detector: photodetector) for downlink signal reception. , WDM optical filter to separate uplink/downlink signals.

Fig. 9 shows a conventional module method. A basic structure of a single-core bidirectional (BIDI: Bi-Directional) module is shown in which optical components including a light emitting element 105 , a light receiving element 102 , and a wavelength selection filter 107 are spatially arranged in a package 108 . In this method, since each optical component can be manufactured independently, it is easy to ensure the manufacturing yield. In addition, since it is possible to optically connect to the optical fiber 109 in an active alignment manner, the so-called active alignment method is to operate the optical elements 105, 102 mounted on the CAN packages 103, 106 integrated with the lenses 101, 104, respectively. 109 performs optical axis alignment, so there is an advantage that stable optical coupling efficiency can be obtained. On the contrary, the number of parts and the number of processing steps are large, which is disadvantageous in size and cost reduction.

FIG. 10 shows the basic structure of the second mode of the single-core bidirectional module disclosed in "Information Technology Report" vol.107, no.7, R2007-2, pp.7-10. In this example, a light emitting element 112 , a light receiving element 116 , and a wavelength selection filter 113 on a transparent substrate 114 are mounted in one package 117 . The transparent substrate 114 is installed at a predetermined angle by the supporting member 115 . The light-emitting element 112 and the light-receiving element 116 are optically connected to the single-mode optical fiber 110 through the lens 111 . The feature of this example is the realization of miniaturization of the module in which all optical parts are mounted in one package. However, the case where the light emitting element 112, the light receiving element 116, and the wavelength selection filter 113 need to be three-dimensionally arranged is the same as the first example, and high-precision mounting is required on the basis of miniaturization, and there is a problem that the alignment process becomes complicated. . Furthermore, when scalability is considered, for example, in the case of a 3-wavelength bidirectional optical module, the number of optical components and the mounting area need to be at least approximately doubled, and miniaturization and cost reduction have become increasingly difficult.

In order to balance wavelength scalability with miniaturization and cost reduction, it is necessary to implement an optical multiplexer/demultiplexer in a compact space. As a compact optical multiplexer/demultiplexer, there is a method of mounting a plurality of filter units on a common parallelogram or other optical blocks. For example, in the multiplexing device disclosed in Japanese Patent Laid-Open No. 61-103110, as shown in FIG. A predetermined position of the substrate 124 that is transparent to the wavelength of light passing through the substrate.

The optical fiber 122 propagating the outgoing light 120 and the incident light 121 is optically connected to a multiplexer and demultiplexer including a transparent substrate 124 via a rod lens 123 . In the multiplexer/demultiplexer 124 , the light passes through each optical filter to sequentially transmit light of a specific wavelength and reflect light of other specific wavelengths, and the light forms a zigzag optical path. Each filter removes or adds specific wavelengths of light. However, the structure disclosed in FIG. 11 couples the optical elements 136 , 137 , 138 and the multiplexer/demultiplexer 124 via rod lenses 130 , 131 , 132 and optical fibers 133 , 134 , 135 . The number of components is large, and miniaturization is difficult.

[Patent Document 1] Japanese Patent Application Laid-Open No. 61-103110

[Non-Patent Document 1] Information Science and Technology Journal vol.107, no.7, R2007-2, pp.7-10

As described above, in the prior art, if the mounting of optical elements is also included, there are many mounting steps of optical components. While the positional accuracy of the wavelength demultiplexer is required, especially a small relative angular misalignment margin, and high-precision mounting is required, it is difficult to ensure yield. Furthermore, in consideration of scalability, the number of optical components and the mounting area need to be approximately doubled, and miniaturization and further high-precision mounting of optical components are required, so it is becoming more and more difficult to ensure yield.

Contents of the invention

The object of the present invention is to provide a low-cost optical module.

Therefore, the object of the embodiments of the present invention is to provide an optical module that guarantees low loss for a terminal used as a wavelength multiplexed optical transmission and a single-core bidirectional optical transmission that transmits light of multiple wavelengths through one optical fiber. Excellent optical characteristics and high reliability, while greatly reducing the installation process, can realize optical modules with miniaturization and high yield.

The spirit of the present invention is as follows.

An optical module, characterized in that it comprises:

The base is set on the CAN socket;

at least a first light-emitting element and a first light-receiving element that are provided on one surface of the base and use wavelengths different from each other;

a CAN cover fixed on said base and having a hole for light in and out at its top; and

The optical multiplexer and demultiplexer is in the shape of a parallel plate, and has a first wavelength selection filter on one surface of the first substrate having transmittance to passing light, and a first wavelength selection filter is provided on the other surface opposite to the one surface. mirror;

In the state where the extension direction of the optical multiplexer/demultiplexer is inclined at an angle θ relative to one surface of the optical element loading substrate on a two-dimensional cross-section, it is fixed in the CAN cover or CAN package (the package can be It is not a CAN package, it can also be other packages, for example, it can also be a package with an optical element sealed. The same below), where, θ≠2Nπ, N=0, 1, 2...;

The outgoing light from the first light-emitting element passes through the first wavelength selective filter and the first substrate, and then enters the optical fiber outside the cover;

The outgoing light from the optical fiber is incident on the optical multiplexer/demultiplexer, reflected by the first wavelength selection filter, and then reflected by the mirror, exits the optical multiplexer/demultiplexer, and enters the optical multiplexer/demultiplexer. The first light receiving element.

Description of drawings

Fig. 1 is a cross-sectional view of a three-wavelength bidirectional optical transceiver module as a first embodiment of the present invention;

FIG. 2 is a diagram illustrating the function of the optical module of the first embodiment of the present invention;

3 is a cross-sectional view of a two-wavelength bidirectional optical transceiver module as a second embodiment of the present invention;

4 is a cross-sectional view of an optical module according to a third embodiment of the present invention, showing a structural example of packaging when the optical modules of the first to second embodiments are coupled to a single-mode optical fiber;

5 is a structural diagram of a planar optical module according to a fourth embodiment of the present invention;

6 is a structural diagram of an optical module as a fifth embodiment of the present invention;

7 is a cross-sectional view of an optical element package constituting an optical module as a fifth embodiment of the present invention;

8 is a cross-sectional view of an optical module according to a sixth embodiment of the present invention;

Fig. 9 is a basic structural diagram of a BIDI module as a first mode of an existing module;

FIG. 10 is a basic structural diagram of a single-package BIDI module as a second mode of an existing module;

Fig. 11 is the basic structure of an optical multiplexer/demultiplexer in the prior art.

reference sign

1...Optical component mounting substrate, 2...Optical multiplexer/demultiplexer, 3...CAN package, 4...Lens, 5...Glass substrate, 6...First wavelength selection filter, 7...Second wavelength selection filter, 8 …first mirror, 9…second mirror, 10…base, 11…light-emitting element, 12, 13…light-receiving element, 14…CAN socket, 15…triplexer module, 16…BiDi module, 21…pigtail Module housing, 22...Single-mode fiber, 23...Sleeve, 30...Plane module housing, 32...Lens, 34...Single-mode fiber, 41...Optical components mounted in CAN package, 50...Inclined CAN package, 101, 104 …lens, 102…light-receiving element, 103, 106…CAN package, 105…light-emitting element, 107…wavelength selective filter, 108…package, 109…single-mode fiber, 110…single-mode fiber, 111…lens, 112… Light emitting element, 113...wavelength selection filter, 114...transparent substrate, 115...supporting part, 116...light receiving element, 117...package, 120...exiting light, 121...incident light, 122, 133, 134, 135...optical fiber, 123, 130, 131, 132...rod lens, 124...optical multiplexer, 125, 126...mirror, 127, 128, 129...wavelength selection filter, 136, 137, 138...semiconductor light-emitting element or light-receiving element.

Detailed ways

The means for solving the technical problem of the present invention will be described with reference to FIG. 1 . FIG. 1 is an example of applying the present invention to a module called a so-called optical triplexer using a bidirectional optical transmission and reception module with three wavelengths.

As shown in FIG. 1 , the present invention prepares a plurality of optical elements 11, 12, 13 (more specifically, a light emitting element 11 and light receiving elements 12 and 13.) Mounted on the same plane of the optical element mounting substrate 1 (in The structure after the optical elements 11, 12, 13 are loaded on the base (sub mount) 10 is referred to as the optical element mounting substrate 1) and the wavelength selection filter and the mirror are typically mounted on the surface and back of the transparent substrate. Optical multiplexer and demultiplexer 2. Installed in the package 3, so that relative to one surface of the substrate 1, the optical element mounting surface and the surface of the optical filter respectively form non-parallel angles (θ≠180 degrees). On the inner surface of the package 3, for example, unevenness is provided for non-parallel mounting of the optical multiplexer/demultiplexer 2 and the optical element mounting substrate 1 . Optical elements using different wavelengths are mounted at predetermined positions on the optical element mounting substrate 1 . The optical multiplexer and demultiplexer 2 uses a substrate with a predetermined thickness made of a material transparent to the wavelength of light used as a support substrate with a pair of parallel opposite surfaces, and at least one wavelength is set on one of the pair of parallel surfaces. The selection filter is provided with a mirror for reflecting the light of the wavelength selected by the first filter on the other surface. In this case, windows for input and output are provided on these filters and mirrors.

Next, the operation of the module of the present invention will be described. The light of the wavelength λ1 emitted from the light emitting element 11 reaches the first wavelength selection filter 6 . The light-emitting element 11 is optically connected to the optical fiber, so that the first wavelength selective filter 6 transmits the wavelength of λ1, refracts it through the transparent substrate, moves the optical path in parallel, and enters the external optical fiber (not shown) through the package lens 4 . At the same time, the optical fiber and the above-mentioned light receiving elements 12, 13 are optically connected so that the light of wavelength λ2, λ3 emitted from the optical fiber is incident on predetermined light receiving elements 12, 13, respectively.

The multiplexed light of the wavelengths λ2 and λ3 emitted from the optical fiber is incident on the transparent glass substrate 5 , is refracted, and then reaches the first wavelength selection filter 6 . The wavelengths λ2, λ3 are reflected to reach the opposite first mirror 8 . The light reflected by the first mirror 8 is incident on a position different from the initial incident position on the first filter surface. In the simplest design, the light once reflected by the first mirror 8 enters the second filter, but in this structure, the reflected light from the first mirror 8 enters the filter 6 again. , and another back-and-forth design is carried out between the optical filter 6 and the first mirror 8 . The light that reciprocates between the filter 6 and the first mirror 8 enters the second wavelength selection filter 7 . Here, the wavelength λ2 and the wavelength λ3 are separated, and the wavelength λ2 is refracted through a filter, and is vertically incident on the light receiving element 12 . On the other hand, the wavelength λ3 is reflected by the second filter and enters the second mirror 9 . The light reflected by the second mirror 9 passes through the interface without a filter (but has an AR coating) and enters the light receiving element 13 .

As explained above, the two planes constituting the optical multiplexer/demultiplexer 2 are installed at an angle that is not perpendicular to the incident light from the optical fiber and the optical axis of the light emitting element 11, whereby the light is obliquely incident on the wavelength selection filter. In arrays and mirror arrays, specific wavelengths of light are removed or added at the intersection of each filter and the optical axis. That is, the above-mentioned two planes are inclined by an angle θ1 relative to the surface of the base 10, so that the two planes and the optical axis of the light incident on the optical multiplexer 2 become an angle other than 90 degrees, that is, non-orthogonal The angle of the optical multiplexer/demultiplexer 2 is installed relative to the CAN stem 14 or the CAN cap 3 . Figure 1 is a cross-sectional view, based on the principle that the above-mentioned value of the angle θ1 does not change along the depth direction of the paper.

FIG. 2 quantitatively shows the function of the wavelength combiner 2 in the structure of FIG. 1 . As shown in FIG. 2 , the positional relationship of the optical axes of light of each wavelength is expressed as a function of the thickness and angle of the glass substrate. For example, as shown in Figure 2, it is a relationship related to x, y, and z. Therefore, if the output end or the input end of each element is arranged in the extending direction of the optical axis determined uniquely by design, optical coupling between the optical fiber and the optical element can be achieved.

Thus, since the first feature of the present invention is to automatically align a plurality of optical filters by aligning the glass substrate only once, the installation process of the device of the present invention is greatly reduced.

The second feature is that since the LD and PD are planarly mounted on the optical element mounting substrate, the mounting can be greatly simplified and high-precision mounting can be performed compared with the case of three-dimensional mounting as in the prior art. When aligning, since each optical element is mounted on a substrate and aligned, the number of steps can be reduced compared to the case of aligning each element individually.

As shown in Figure 2, when the angle formed by the substrate plane relative to the surface of the base 10 is θ ₁ , the light from the optical fiber or optical element 11 in the vertical direction relative to the substrate surface to the optical multiplexer and demultiplexer 2 The incident angle (incident angle) of is θ ₁ . The angle θ ₂ inside the substrate material after refraction is according to Snell’s law, using the refractive index n ₁ outside the substrate 2 and the refractive index n ₂ of the substrate 2, it is θ ₂ =sin ^-1 (n ₁ ·sinθ ₁ /n ₂ ).

At this time, the period y of multiple reflection inside the substrate can be given as 2d tanθ ₂ , assuming that the thickness of the transparent substrate is d. When the multiple reflected light is wavelength-separated by an optical filter according to the above-mentioned principle, when it exits on a plane perpendicular to the optical axis at the time of incidence, its period z can be given as 2dsinθ ₂ ·cosθ ₁ . Since the period z corresponds to the spacing of components mounted on the component mounting substrate, d, θ ₁ needs to be selected so as to maintain an appropriate component spacing. Since the size of the element is less than 100 μm, the value of z needs to be 100 μm or more.

【Effect of invention】

According to the present invention, it is possible to provide a low-cost optical module compared with the prior art.

According to an embodiment of the present invention, for an optical transmitting module that combines multiple wavelengths of light to transmit, or an optical receiving module that divides the combined light for each wavelength to receive, or a single-core bidirectional optical transmitting and receiving module The module maintains low-loss optical characteristics and high reliability, and greatly reduces the number of optical components and the number of installation processes, and can provide a miniaturized optical module capable of achieving high yield and a manufacturing method thereof.

Examples are described in detail below.

(Example 1)

FIG. 1 is a cross-sectional view of an optical module as a first embodiment of the present invention. FIG. 1 is an example of applying the present invention to a module called an optical triplexer using a three-wavelength bidirectional optical transmission and reception module.

Fig. 1 is the example that is installed on the CAN package, the optical element mounting substrate 1 after the light-emitting element 11 and the light-receiving element 12, 13 are loaded on the base 10 is installed on the CAN socket 14, and the optical multiplexer and demultiplexer 2 Installed on the CAN cover 3 to form a triplexer module 15 . The operating wavelengths of the optical elements 11 , 12 , and 13 are λ1 , λ2 , and λ3 , respectively, and the length relationship of the wavelengths is λ1<λ2<λ3. However, the magnitude relationship of wavelengths is not limited to this. In FIG. 1 , the optical elements are arranged from elements using shorter wavelengths to elements using longer wavelengths. Concave-convex for installing optical multiplexer/demultiplexer is provided inside the CAN cover 3 . Wherein, it is sufficient that the optical multiplexer and demultiplexer can be fixed inside the CAN cover 3 . Regardless of the fixed means. Therefore, it is not necessary to provide concavities and convexities, and instead of concavities and convexities, for example, a notch is provided in the packaging component so that, for example, the optical multiplexer/demultiplexer and the packaging component can be fitted together. Alternatively, the package member may have both concavities and convexities and notches.

The optical multiplexer and demultiplexer 2 uses the transparent glass substrate 5 as a support substrate, and a first wavelength selection filter 6 and a second wavelength selection filter 7 are installed adjacently on one face, and on the opposite side parallel to the face Install the first mirror 8 and the second mirror 9 on the surface. The installation of the optical multiplexer and demultiplexer is carried out by matching the concave-convex shape of the CAN cover, and bonding with UV-curable resin. The material of the glass substrate is BK7, and the thickness is 1136 μm. Install the glass substrate so that the angle relative to the plane is 20°, and z in FIG. 2 , that is, the projection of the pitch of multiple reflections on the plane is 500 μm. The wavelength selective filter is composed of a dielectric multilayer film composed of Ta ₂ O ₅ and SiO ₂ . The first wavelength selection filter 6 is an optical filter having a separation wavelength λ _th of λ ₁ <λ _th <λ ₂ , and having a property of transmitting light of a wavelength shorter than the λ _th and reflecting light of a longer wavelength. (so-called short pass filters). The second optical filter 7 is a short-pass filter whose separation wavelength is λ ₂ <λ _th <λ ₃ . The first mirror 8 is used the same as the first wavelength selective filter 6 , and the second mirror 9 is used the same as the second wavelength selective filter 7 . As the light-emitting element 11 on the optical element-integrated substrate, a vertical emission type LD integrated with a microlens is used. The light-emitting element 11 may also use an end surface emission type LD, but a vertical emission type is preferable from the viewpoint of ease of mounting, and a lens-integrated type is preferable from the viewpoint of ease of optical coupling and reduction in the number of parts. For the same reason, the light-receiving elements 12 and 13 are also preferably of the surface incidence type. Amplifiers and capacitors are also installed in CAN, but these are the same as usual, so they are not shown in the figure.

The material of the transparent substrate 5 may be transparent to the wavelength used, but it is not limited thereto, and it is preferably a material with low price and good processing accuracy. As a material satisfying this condition, BK7 is used in this example, but other glass materials, dielectrics, and semiconductors may of course be used.

The operation of this configuration example will be described. The light of the wavelength λ1 emitted from the light emitting element ₁₁ reaches the first wavelength selection filter 6 . The first wavelength selection filter 6 transmits the wavelength of _λ1 , refracts through the transparent substrate, and moves the optical path in parallel, and connects with the external optical fiber through the packaging lens 4. On the other hand, the multiplexed light of the wavelengths λ ₂ and λ ₃ emitted from the optical fiber enters the transparent glass substrate, is refracted, and reaches the first wavelength selection filter 6 . The wavelengths λ ₂ , λ ₃ are reflected and reach the opposite first mirror 8 . The first mirror 8 is identical to the first wavelength selective filter 6 so that the wavelengths λ ₂ , λ ₃ are reflected again. Using the same first mirror 8 as the optical filter 6 here is to improve the blocking ability to the wavelength _λ1 . The light of wavelength λ1 emitted from the light-emitting element ₁₁ is slightly reflected on the surface of the lens 4 and the end surface of the optical fiber, and becomes return light, which enters again. Even if the return light of this wavelength _λ1 is a slight amount of light, when it enters the light receiving elements 12 and 13, it becomes noise. The returned light of _λ1 passes through the filter 6, but is reflected by a slight amount. Therefore, the light quantity is further reduced by being transmitted again in the first mirror 8 . For the above reasons, in this embodiment, the same first mirror 8 as the optical filter 6 is used, and when the wavelength separation standard is not strict, it is sufficient to use a normal mirror without wavelength dependence.

The light reflected by the first mirror 8 enters the filter surface again. In the simplest design, the light reflected by the first mirror 8 enters the second filter, but in this structure, the reflected light from the first mirror 8 enters the filter 6 again. , and another round-trip design is performed between the optical filter 6 and the first mirror 8 . This is because the distance between the light-emitting element 11 and the light-receiving element 12 is larger than the projection of the multiple reflection pitch. This is because the light-emitting element driven at high speed may become a noise source on the light-receiving element side (this is called electrical crosstalk). If there is no special reason such as electrical crosstalk, it is preferable to minimize the number of reflections by making the pitch of multiple reflections in the glass substrate coincide with the mounting pitch of components.

The light that has made two round trips between the filter 6 and the first mirror 8 is incident on the second wavelength selection filter 7 . Here, the wavelength λ ₂ and the wavelength λ ₃ are separated, and the wavelength λ ₂ passes through the filter and is refracted, and is vertically incident on the light receiving element 12 . On the other hand, the wavelength _λ3 is reflected and enters the second mirror 9. The second mirror 9 uses the same dielectric multilayer filter as the filter 7 for the same reason as that of the first mirror 8 . The light reflected by the second mirror 9 passes through the interface without a filter (but has an AR coating) and enters the light receiving element 13 .

(Example 2)

Fig. 3 is a cross-sectional view of an optical module according to a second embodiment of the present invention. This embodiment is a configuration example in which the present invention is applied to a two-wavelength single-core bidirectional (BIDI: Bi-Directional) module. As shown in FIG. 3 , the BIDI module 16 is the same as the first embodiment in that it is composed of an optical element mounting substrate 1 , an optical multiplexer/demultiplexer 2 , and a CAN package 3 . However, since the BIDI module transmits and receives at two wavelengths, one upstream wavelength and one downstream wavelength, the only optical elements mounted on the optical element mounting substrate 1 are the light emitting element 11 and the light receiving element 12 . On the optical multiplexer/demultiplexer 2, one type of optical filter 6 and first mirror 8 are respectively installed.

(Example 3)

Fig. 4 is a cross-sectional view of an optical module according to a third embodiment of the present invention. This embodiment is an example in which the present invention is applied to a so-called pigtail type module with optical fibers. As shown in FIG. 4 , the triplexer module 15 of the first embodiment of the present invention is installed on the coaxial square module housing 21 , and an optical fiber 22 with a ferrule is further installed through a sleeve (sleeve) 23 . In this example, an example of a pigtail type module is shown, but a removable type (resectable) module can also be configured with the same structure.

(Example 4)

FIG. 5 is a diagram showing an optical module according to a fourth embodiment of the present invention. This embodiment is an example of mounting on a planar package. As shown in Figure 5, the structure of the triplexer module is installed on a planar package 30: an optical element loading substrate 1 on which a light-emitting element 11 and light-receiving elements 12, 13 are installed on a base 10; Waveform 2, lens 32 and single mode fiber 34. As shown in FIG. 10 , in this embodiment, an optical element mounting substrate 1 on which an optical element is surface-mounted is mounted vertically from the bottom surface of the planar package. As a planar package, for example, a butterfly package can be used. In the form shown in FIG. 5 , three wavelengths are supported, but even if the number of wavelengths is further increased, it is possible to cope relatively easily, which is a feature of this mounting method.

(Example 5)

6 and 7 are diagrams showing an optical module according to a fifth embodiment of the present invention. The feature of this module is that only the optical components are pre-concentrated in one package, and they are installed in other packages together with the optical multiplexer and demultiplexer. The structure of this module is as shown in FIG. 5 . The optical element loading CAN package 41 , optical multiplexer and demultiplexer 2 , lens 32 and single-mode optical fiber 34 are installed on the planar package 40 . The structure of the CAN package 41 for mounting optical elements is as shown in FIG. 6 , and the substrate 1 for mounting optical elements 11 , 12 , and 13 is mounted thereon. In this example, an example of a planar package is shown, but a module case other than the planar type, such as a coaxial type package, may also be used.

(Example 6)

FIG. 8 is a diagram showing an optical module according to a sixth embodiment of the present invention. This embodiment is an example in which an optical multiplexer/demultiplexer is attached to the window portion of the cover of the CAN package. Usually an encapsulation lens or flat glass is mounted on the cover of the CAN module. As shown in Figure 8, in the module of this example, the upper surface of the CAN package is at a non-parallel angle to the CAN socket 14, and by installing the optical multiplexer and demultiplexer 2 on its window, the integration of the optical multiplexer and demultiplexer 2 with the optical element is realized. The loading substrate 1 is held non-parallel. Since tilted CANs with tilted windows are widely used, the fabrication of the CAN package 40 of this example does not require special costs. As a method of mounting the optical multiplexer/demultiplexer 2 in the CAN package 40 , for example, low-melting-point glass may be used.

In Fig. 8, an example of the structure of sealing the window of the CAN package by the optical multiplexer/demultiplexer 2 is shown, but it is also possible to seal the window by a common plate glass, and paste the optical multiplexer/demultiplexer on the bottom or top of the plate glass. The structure of device 2.

Claims (9)

1. An optical module, characterized in that, comprising: CAN socket; a base, set on the CAN socket; a first light-emitting element and a first light-receiving element that are provided on the first surface of the base and use wavelengths different from each other; a CAN cover fixed on said base and having a hole for light in and out at its top; and Transparent substrate, which is transmissive to passing light; An optical fiber is optically connected to the hole for entering and exiting light; The transparent substrate is fixed in a state where the extension direction is inclined by an angle θ in a two-dimensional cross-section relative to the first surface of the base, where θ≠2Nπ, N=0, 1, 2...; The light-emitting element is a vertical emission laser; A first wavelength selective filter is provided on the first surface of the transparent substrate, and a mirror is provided on the second surface opposite to the first surface of the transparent substrate; The outgoing light from the first light-emitting element is incident on the optical fiber after passing through the first wavelength selection filter and the transparent substrate; The outgoing light from the optical fiber enters the transparent substrate, is reflected by the first wavelength selection filter, is reflected by the mirror, exits the transparent substrate, and enters the first light receiving element. , The end portion of the transparent substrate is fixed at a predetermined angle by the concavo-convex inside the CAN cover. 2. The optical module according to claim 1, characterized in that: A second wavelength selective filter is provided on the first surface of the transparent substrate; A second light receiving element is provided on the first surface of the base. 3. The optical module according to claim 2, characterized in that: The light incident from the optical fiber is wavelength multiplexed light having wavelengths λ2 and λ3, where λ2≠λ3; The wavelength multiplexed light is incident on the transparent substrate, reflected by the first wavelength selective filter, and then reflected by the mirror, and the light of the wavelength λ2 passes through the first surface of the transparent substrate The set second wavelength selection filter is incident on the first light-receiving element; The light having the wavelength λ3 is reflected by the second wavelength selection filter, is reflected by the mirror, exits the transparent substrate, and enters the second light receiving element. 4. The optical module according to claim 1, characterized in that: When the light emitted from the optical fiber is reflected by the first wavelength selective filter and reflected again by the mirror arranged opposite to the first wavelength selective filter, the mirror has a transmission The characteristics of the light in the transmission band of the first wavelength selection filter. 5. The optical module according to claim 1, characterized in that: The mirror is the same wavelength selection filter as the first wavelength selection filter located before the mirror on the optical path. 6. The optical module according to claim 1, characterized in that: The material of the transparent substrate is glass material, dielectric or semiconductor. 7. The optical module according to claim 1, characterized in that: The light emitting element is a lens-integrated type. 8. The optical module according to claim 2, characterized in that: The light emitted from the optical fiber or the first light-emitting element is incident on the first surface of the transparent substrate at an incident angle θ ₁ , and is emitted at an outgoing angle θ ₂ , and passes through the first wavelength selection filter and In the process of multiple reflection of incident light between the second wavelength selective filter and the mirror, light with different wavelengths is separated or overlapped, wherein θ ₁ ≠90 degrees, θ ₂ ≠90 degrees; The projection z of the pitch of the multiple reflection on the plane, the distance d between the first surface of the transparent substrate and the second surface of the transparent substrate, the first surface of the transparent substrate relative to the first surface of the base The relationship between the inclination angle θ ₁ of the surface, the external refractive index n ₁ , and the refractive index n ₂ of the casing satisfies z=2d tanθ ₂ cosθ ₁ ≥ 100 (μm). 9. The optical module according to claim 2, characterized in that: The light emitted from the optical fiber or the first light-emitting element is incident on the first surface of the transparent substrate at an incident angle θ ₁ , and is emitted at an outgoing angle θ ₂ , and passes through the first wavelength selection filter and In the process of multiple reflection of the incident light between the second wavelength selective filter and the mirror, light with different wavelengths is separated or overlapped, wherein θ ₁ ≠90 degrees, θ ₂ ≠90 degrees; When the distance between the first surface of the transparent substrate and the second surface of the transparent substrate is d, the optical axis of the outgoing light of the first light-emitting element and the incident light from the optical fiber reach the second surface of the transparent substrate. The distance x between the optical axes on plane 1 satisfies x=d sin(θ ₂ −θ ₁ )/cos θ ₂ (μm).

Images